Back when you could (more easily) glitch under the map in the grottos, I explored all of Rasputin's bunker from the outside. I went in via patrol, a couple of missions, and the saber strike to see if different parts loaded. The vents you're talking about have short tunnels behind them for aesthetics. Most lead nowhere. Two connect to a small room with nothing in it. What you see behind them is just bungie being thorough with their map design, and currently lead no where relevant. The one exception is one of the vents near the end of the saber strike that has a dead ghost behind it. This vent is breakable and the ghost widely known.